A) Field of the Invention
This invention relates to a lead frame to be mounted to a semiconductor chip.
B) Description of the Related Art
For example, a semiconductor chip formed by a photolithography process is packaged via bonding after mounting to a lead frame. Recently a multi-chip package that mounts plurality (two or more) of the semiconductor chips on a single lead frame is widely used. In the multi-chip package, plurality of stage units to be mounted onto these semiconductor chips corresponding to the numbers of the semiconductor chips are equipped (Refer to JPA H01-308058). Each stage unit is supported by a frame unit on the outskirt by a supporting unit for supporting.
When the plurality of the stage units are equipped, there is a risk for each stage unit to be deformed in following processes such as a packaging process, etc. For example, when resin is injected in the packaging process, each stage unit may be buffeted by the flow of the resin. If the stage is buffeted, an electrical damage such as cut in a bonding wire may occur. Therefore, in the multi-chip package, each of two stage units is supported by a supporting unit independently. Moreover, two stage units are connected by a united connection unit to reduce deformation of the stage unit (refer to JPA 2005-64076).
However, when each stage unit is supported by the supporting unit, it is necessary to equip at least a supporting unit extending from each angled part of the stage units to the frame units in order to support the stage units stably. On the other hand, plurality of inner leads to be connected with the semiconductor chips mounted on the stage units are equipped on the frame unit. Therefore, a unit of the inner leads is used as the supporting unit, and the inner leads that can be usable for connecting with the semiconductor chips will decrease. As a result, it may cause large sizing of the frames in order to reserve predetermined number of the inner leads.
Moreover, in the multi-chip package, for example, a signal-type large scale integrated circuit (LSI) driven at a low voltage of about several volts for processing signals and a controlling-type switching element for a controlling system driven by this signal-typed LSI at a high voltage of from about several tens volts to several hundreds volts are mounted on the same lead frame. In this case, difference in electric potentials between the stage unit mounting the signal-typed LSI and the stage unit mounting the controlling-typed switching element becomes large. Therefore, it is necessary to insulate the two stage units. As a result, if the two stage units are connected by a united connection unit as disclosed in JPA 2005-64076, there will be a problem that it is impossible to insulate the two stage units.